Reverberatory furnace



Oct. 6, 1953 I D, KNlGHT 2,654,593

REVERBERATORY FURNACE Filed Aug. 6, 1949 2 Sheets-Sheet 2 INVENTOR. by DEE A. KNIGHT ATTORNEY Patented Oct. 6, 1953 UNITED STATES OFFICE 2,654,593" REVERBERATORY roance Dee A. Knight; Lawson, Colo; Application:August s, 1949-, Serial Moi-109,020

1 Claim.

This invention relates, to furnaces forthe continous heat-treating and heat-processing of,

inal material may warrant, and has as an object to provide an improved reverberatory-type fur.- nace of high efficiency and wide adaptability.

A further object of the invention is to provide an improved reverberatory-type furnace char-.-

acterized by a novel heat circulation therein. A further object of the invention is .to pro vide an improved reverberatory -type furnace:

characterized by heat circulation over and. about both upper and lower surfaces, of 1 a hearth,

whereby to enhance the operating efficiency of the furnace.

A further object of the invention is to provide,

an improved reverberator-y-type furnace adapted to isolate and entrap for separate :recoverythe constituents of natural materials fusible at temperatures within the capacity of the unit.

A further object of the invention is toprovidean improved reverberatory-type furnace con.- tinuously cooperable with various types of material feeds capable of introducing the material to be treated into and across the path. of heat circulation within the furnace.

A further object of the-invention. is .to provide an improved reverberatory-type furnace suscep tible of operative association with various types and constructions of heat generators.

A further object of the invention is to provide an improved reverberatory-type furnace susceptible of convenient, economical construction from known and available materials in any desired size and capacity, that is readily adaptable to the desired heat-treatment of a particular material, that is convenient and practical of multiunit correlation in a single bank, durable and long-lived in use, and simple of maintenance, operation, and rehabilitation.

With the foregoing and other objects in view, my invention consists in the construction, arrangement, and combination of elements hereinafter set forth, pointed out in my claim, and

illustrated by the accompanying drawings, in,

which- Figure 1 is a vertical section taken-longitudinally through a typical furnace embodying the principles of the invention. Figure 2"is a transverse section vtaken substantially on the indicated line 2 -2 of Figure .1., Figure 3 is a section similar to Figure :1 illustrating an alternative hearth construction. Figure 4 isa section similar to.

FigureS illustrating an alternative materialsfeed arrangement. Figure 5 isa plandiagram of one multi-unit bank arrangement "to which the improvement is adaptable. Figure 6 is a plan diagram of a second .multi-unit'bank arrangement to which the improvement is adaptable.

In the: construction of the improvement as shown, a furnace enclosure of desired size and appropriate proportionsis defined'between upright, spacedly parallel sidewalls lfl'upstanding' from margins of a floor. H, afront end wall I 2' perpendicular to andiclosing, between forward ends of said side vWall's. andfioor, a rear end Wall I3- spacedly paralleling said front end Wall in closing relation between rearward ends of said sidewalls and. floor, and la roofM bridging and covering 1 between upper margins of said side Walls andfrontand rear. .end walls. As is customary practice, the enclosure-defining. elements In, ll, 12, l3 and..l4 are built upv from, or at least interiorly faced with, refractory material,

such as fire-brick, in a. manner facilitating renewal and rehabilitation .of the element surfaces exposed to high .temperatures, the floor I l and wall lower margins may bear upon. a plate l5 supported by a grid of structural members It, and the side walls. [0 maybe stiffened and reinforced against heat-developed distortions by means of. structural. member grids I! bearing against their exterior surfaces and interlinkedin awell-known arrangement to assist the structural andoperativestresses to which said 'walls are subject. Conforming with conventional practice innreverberatory furnace construction, the inner, downwardly-directed. face of the roof I 5 is. transversely arched and concaved between the side walls l0,. both for structural considerations and tospreadandsuitably direct heat and flame impinging .thereagainst. during furnace operation,. and said roof inner face merges into and with the inner face of 'the rear end wall I3 through a smoothly-concaved arch H3 longitudinally of the furnace enclosure and at the rear end thereof for direction of heat and flame circulation within the furnace in accordance with typical 3 the side walls It in suitably-spaced relation above the floor I I, said hearth extending longitudinally of the furnace enclosure in a substantially horizontal disposition from a closed junction of its rearward end with the rear end wall l3 to termination at its forward end in spaced relation with the inner face of the front end wall l2, thereby to leave a throat or passage past the forward end of the hearth for free and unobstructed communication between the furnace enclosure compartments above and below said hearth. In a preferred construction, the altitudinal spacing between opposed surfaces of the floor H and hearth [9 will be approximately one-half the altitudinal spacing between opposed surfaces of said hearth and the roof l4 and'the vertical throat opening past the forward end of the hearth will have a flow capacity approximating that of the open area between the floor and hearth, the curve of the arch l8 merging into the rear end wall inner face well above the junc-' tion of the latter with the hearth upper surface. For certain heat-processing operations, the upper surface of the hearth l9 may be substantially plane and horizontally flat,'as shown in Figures 1 and 2, while for other particular processing operations it is expedient that said hearth upper surface be concaved longitudinally of the furnace, as shown in Figures 3 and 4 or be concaved both laterally and longitudinally of the furnace, to constitute a basin or reservoir therein.

However particularly constructed and proportioned, the improved furnace is fired through and by means of a burner, typically represented at 20, operatively disposed through the front end wall l2 substantially on the vertical median line thereof and well above the top plane of the hearth it at such upward and inward inclination as will engage its heat discharge against the roof ii in and at the area of roof junction with the arch 52. The burner indicated at 2B is but representative of various conventional analogous units powered and pressurized in various ways for the production of a high temperature flame ejection incident to the combustion of a suitable fuel, such as oil, gas, pulverized coal, and the like, supplied to the burner, the improved furnace being hence adaptable to operation with an available or preferred fuel through selection and installation of an appropriate burner 2i). burner 28 and with its lower margin at or slightly above the plane of the hearth I9 upper surface, an access and inspection passage exteriorly closable by means of a door 2| opens through and centrally of the front end wall 12, and a similar passage exteriorly closable by means of a door 22 opens through the lower central portion of said end wall with its lower margin preferably coplanar with the floor H upper surface.

The lower compartment of the furnace enclosure, being that area between the floor H and hearth l9, communicates through a suitable opening centrally of the rear wall l3 lower portion with an initially-horizontal flue 23, preferably of refractory material, through which the gaseous products of combustion had within. the.

furnace may be led, either directly or through intermediate apparatus, to ultimate exhaust through a stack 24. As is well understood, the gaseous products resulting from certain types of heat-processing had through a reverberatory furnace carry values meriting recovery through.

appropriate subsequent processing thereof, such Below the position of the being particularly the case when the furnace is applied to effect subliming operations, and suitable filters, condensers, collectors, and analogous apparatus may be interposed in the path of gaseous product travel between the flue 23 and stack 24 for the working and processing of such products in accordance with established practice.

The improved furnace is adapted for feed of material to be processed thereto and into the high temperature circuit thereof in any convenient and appropriate manner. As represented in Figures 1, 2 and 3, a hopper 25 on and extending above the roof I4 may be arranged to communicate through a vertical throat on the longitudinal median line of the furnace with the k upper compartment of the latter adjacent or just forwardly from the junction of the roof inner surface horizontal portion with the arch [8, so that material to be treated delivered to the hopper 25 may be fed thence, either mechanically or by gravity, through said throat and into the zone of burner flame impingement against said roof. Alternatively, and as represented in Figure 4, a power-reoiprocable, mechanical plunger 26 may be operatively mounted exteriorly adjacent the rear end wall is in registration with a feed throat opening through said wall just above the hearth l9 upper surface,

- in which event the material to be treated is delivered adjacent the outer end of said feed throat for mechanical feed therethrough and to the rearward end of the hearth l9 as a consequence of plunger 26 actuation.

In association with the concaved hearth [9 of Figures 3 and 4, selectively valve-controlled flow outlets 2'! and 28 may be advantageously employed for the separate recovery of liquid prod ucts during continuous furnace operation, it being expedient to altitudinally space the outlets 21 and 28 so as to position the one for outflow of liquid dross or slag floating on a body of heavier molten material and to dispose the other for draining of the heavier material from the hearth concavity.

Practical considerations of maintenance and operation point the advisability of cooling the exterior vertical walls and hearth of the improved furnace, to which end metallic jackets 29 may be embedded in said walls and hearth in any suitable or desired capacity and arrangement and in any desired operative association in and with a coolant circulating system, not shown; conservation of heat otherwise lost during furnace operation resulting when the coolant circulating system is arranged to apply the heat elevation of the coolant leaving the furnace jackets to useful work and effect.

As represented in Figures 5 and G, the improved furnace is well-adapted to the development of multi-unit furnace banks wherein each unit is a complete furnace of the type and characteristics above elaborated, such bank development involving only appropriate disposition of the separate furnace units in either spaced or juxtaposed parallelism and manifolding of the supply to their respective burners 2i} and similar manithe rear ends. of the furnace unitsand deliver to a common manifold leading exteriorly of the furnace bank to the stack 26, either directly or through intermediate apparatus, while when the,

furnace units are juxtaposed, as in Figure 6, it IS expedient to direct the flues 23 of the respective units laterally and for discharge through the unit side walls in a manner permitting of their alignment in intercommunication and for joint delivery to the stack 24 in the manner shown.

Application of the improved furnace to and its operation in the heat-processing of a given material should be manifest from the foregoing. A salient feature of the improvement is the arrangement and disposition of the hearth 19 to expose both upper and lower hearth surfaces to the path of heat flow through the unit and to determine an S-shaped path of heat flow productive of high processing efiiciency. In subliming operations, material fed from the hopper' 25 passes twice through the heat flow generated by the burner 26 before reaching the hearth l9, and any material coming to rest upon said hearth is still subject to a temperature nearly as great as that of the heat flow circuit and consequently is constrained to give u its volatile constituents retained during material descent, thus effectuating a maximum sublimation with a minimum of residue. Comparably, the high temperature of the hearth l9 deriving from the novel and improved furnace arrangement adapts the unit to the extraction of fusible material constituents through concaving of the hearth upper surface as shown in Figures 3 and 4, the so-concaved hearth functioning as a crucible for the entrapment of the fusibles in maintained molten state and in a manner permitting of selective separation thereof. Residues collected upon the hearth 19 or floor l l are recoverable through manipulations had through the doors 2| and 22, and their associated passages, or otherwise, as may be deemed expedient, and the furnace is efficiently applicable to calcining, explosive disintegration, exfoliation, and extroversion of various materials desired to be recovered as residues or solids, as is readily apparent from the foregoin disclosure.-

Since changes, variations, and modifications in the form, construction, and arrangement of the elements shown and described may be had without departing from the spirit of my invention, I wish to be understood as being limited solely by the scope of the appended claim, rather than by any details of the illustrative showing and foregoing description.

I claim as my invention;

A reverberatory furnace comprising marginally conjoined floor, roof, side, rear end, and front end walls defining a furnace enclosure, a hearth closing against said rear end wall and transversely of the enclosure between said side walls spacedly above said floor with its forward end spaced from said front end wall to define a passage therebetween, a heat-generator serving the upper portion of said enclosure through said front end wall, whereby to establish and maintain a reversed, two-pass flow of heat longitudinally of and above said hearth between said generator and the passage at the forward end of the hearth, a flue outlet serving the lower, rearward portion of said enclosure beneath said hearth, whereby to entrain the flow of heat forwardly along and above the hearth through the passage at the hearth forward end and as a third pass longitudinally of and beneath the hearth, and means for feeding material to be processed to said hearth through the heat travel path of the enclosure thereabove, wherein the hearth upper surface is concaved as a reservoir for the retention of molten material, and said concavity is served by altitudinally-spaced flow outlets for the selective recovery of its contents.

DEE A. KNIGHT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 24,828 Solomon July 19, 1859 158,862 Nicholson Jan. 19, 1875 174,100 Williams Feb. 29, 1876 461,155 Wright Oct. 13, 1891 874,537 Potter Dec. 24, 1907 1,360,798 Riley Nov. 30, 1920 1,363,188 Muckle Dec. 21, 1920 1,554,452 Maskrey Sept. 22,1925 1,682,343 Lanigan Aug. 28, 1928 2,039,738 Pugh May 5, 1936 2,430,477 Morton Nov. 11, 1944 2,572,819 Schaefer Oct. 23, 1951 

